Method for identifying the composition of a sample

ABSTRACT

The present invention is directed to a method for multidimensional gas chromatography for separating the analytes of a complex sample. The method comprises the steps of introducing the sample onto a first column whereby the sample is separated into at least two segments, introducing at least one segment into a heartcut device whereby the segments are selectively separated into at least two heartcut fractions, introducing at least one of the fractions onto a second column whereby at least one fraction is further separated into at least two analytes, introducing at least one analyte from the second column to a gas chromatography connector, introducing the analyte from the connector to a third column, and introducing the analyte from the third column into a detector whereby the analyte is analyzed and identified.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to the U.S.patent application Ser. No. 11/940,684, filed Nov. 15, 2007 which ishereby incorporated by reference to the extent permitted by law.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

BACKGROUND OF THE INVENTION

Gas-liquid chromatography, commonly referred to as gas chromatography orGC, is a process used for analyzing a complex sample by separating theanalytes within the sample to determine the identity of the analytes inthe sample. Other information about the analytes, such as theconcentration of each analyte within the sample, may also be obtained. Agas chromatograph is used for separating the sample by injecting thesample onto a column through which the sample passes. Different chemicalanalytes of the sample pass in a mobile phase at different ratesdepending on their various chemical and physical properties and theirinteraction with a specific column filling, called the stationary phase.During the process of gas chromatography, the analytes of the sample areseparated as a consequence of being partitioned between the mobilegaseous phase and the stationary phase held in the column or by passingthrough a series of columns. The function of the mobile phase is totransport the sample through the column but not to interact with it. Thesample's motion through the column is inhibited by the adsorption of theanalytes either onto the column walls or onto packing materials withinthe column. The rate at which the analytes progress along the columndepends on the strength of adsorption, which in turn depends on theproperties of the analyte. Since each type of analyte has a differentrate of progression, the various analytes of the sample are separated asthey progress along the column and reach the end of the column atdifferent times. A detector is used to monitor the outlet stream fromthe column, thus, the time at which each analyte reaches the outletidentifies the analyte and may determine the concentration of thatanalyte as well.

When a sample is complex and has multiple analytes it may be difficultto separate out and identify a particular analyte of interest. Inmultidimensional gas chromatography the sample undergoes a series ofseparation steps. The sample is introduced to at least two columnsallowing for a better separation of the analytes. Increasing theseparation of the sample increases the accuracy and the precision of theresults. Multiple columns and separation steps allow for a moreeffective separation of the analytes from the sample, but this processdoes not necessarily target a particular analyte. Therefore, it would bebeneficial to have a method that improves the separation of the sampleand allows for the targeting of specific analytes.

The equipment used for chromatography can be expensive and, as complexsamples progress through the chromatograph, build-up occurs. It would bebeneficial to employ a method that keeps the equipment cleaner andreduces the need for maintenance.

SUMMARY OF THE INVENTION

In one of many illustrative, non-limiting aspects of the presentinvention, there is provided a method for identifying the composition ofa sample. The method includes introducing the sample onto a first columnwhereby the sample is separated into at least two segments, introducingat least two segments to a heartcut device whereby at least two segmentsare selectively separated into at least two heartcut fractions,introducing at least one of the fractions onto a second column wherebyat least one fraction is further separated into at least two analytes,introducing at least one analyte from the second column to a gaschromatography connector, introducing the analyte from the connector toa third column, and introducing at least one analyte from the thirdcolumn into a detector whereby at least one analyte is analyzed andidentified.

In another of many illustrative, non-limiting aspects of the presentinvention, there is provided a chromatograph for identifying thecomposition of a sample. The chromatograph includes a first columnwhereby the sample is separated into at least two segments, a heartcutdevice whereby the segments are introduced and then selectivelyseparated into at least two heartcut fractions, a second column wherebyat least one heartcut fractions are introduced and further separatedinto at least two analytes, a gas chromatography connector whereby theanalyte is introduced from the second column, a third column whereby atleast one analyte is introduced from the connector, and a detectorwhereby at least one analyte is introduced from the third column andthen analyzed to identify at least one analyte.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings that form a part of the specification andthat are to be read in conjunction therewith:

FIG. 1 is a schematic diagram illustrating one embodiment of the methodof the present invention.

FIG. 2 is a schematic diagram illustrating one embodiment of the methodof the present invention.

FIG. 3 is a schematic diagram illustrating one embodiment of the methodof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

There is provided herein a method for separating analytes of a complexsample and determining information about the analytes. A device forseparating analytes of a complex sample is also provided. The method ofthe present invention is used to improve the separation of analytes fromthe sample. Improved separation means improved results and betterefficiency of the chromatography process. The method also improves thelifetime of the columns and other equipment, reducing the need formaintenance.

FIG. 1 illustrates one embodiment of the method of the presentinvention. The method for separating analytes of a complex sampleutilizes a chromatograph 10. Chromatograph 10 includes a sampleintroduction device 20, a first column 30, a heartcut device 40, atemperature controlling device 50, a second column 60, a connector andmodulator 70, a third column 80 and a detector 100. The sample isintroduced onto first column 30 by introduction device 20. Introductiondevice 20 may be, but is not limited to, a split/splitless injector, anon-column inlet, a thermal desorption device, a PTV injector, a gassource inlet, a gas switching valve, a purge-and-trap system, a solidmicroextraction, or another injection device now known or hereafterdeveloped that is suitable for injecting the sample onto first column30. First column 30, second column 60, and third column 80 may be, butare not limited to, capillary columns, packed columns, micropackedcolumns, microfast columns, or any other type of column now known orhereafter developed. In an illustrative example, each column is acapillary column with first column 30 and second column 60 each having asize of about 30 m×0.25 mmID×1 μm df, and third column 80 having a sizeof about 1 m×0.10 mmID×0.1 μm df. On first column 30, the sample isseparated into at least two segments. The segments are introduced intoheartcut device 40 and are selectively separated into at least twoheartcut fractions. As an added benefit, heartcut device 40 may removemuch of the sample's matrix leaving second column 60 and detector 100cleaner and reducing the need for maintenance. In one embodiment, a SGEheartcut device is heartcut device 40. In an alternate embodiment, aDean's switch is heartcut device 40. In another alternate embodiment, aGerstel heartcut device is heartcut device 40. In another alternateembodiment, a valve is heartcut device 40. It will be appreciated by onein the art that alternative devices that allow for the selectiveseparation of fractions from the segments may be used in place ofheartcut device 40. In another embodiment, heartcut device 40 isoperably connected to a midpoint detector 110 to aid in setting thecorrect timing for heartcut device 40 to transfer the fractions ontosecond column 60.

In one embodiment, as illustrated in FIG. 1, first column 30 andheartcut device 40 are located within temperature controlling device 50.In an illustrative example, the temperature within temperaturecontrolling device 50 preferably ranges from about 40° C. to 320° C.Temperature controlling device 50 may be, but is not limited to, anoven, a heating jacket, or other appropriate device for controlling thetemperature of the equipment now known or that is hereinafter developed.In one embodiment, second column 60 may also be located withintemperature controlling device 50. At least one of the heartcutfractions is then introduced onto second column 60 whereby at least onefraction is further separated into at least two analytes. At least oneof the analytes is then introduced to connector 70. Connector 70 may be,but is not limited to, a gas chromatography x gas chromatographymodulator that may be either a thermal or valve-based modulator. It willbe appreciated by one in the art that the temperature of temperaturecontrolling device 50 may be customized for the target analytes. Atleast one analyte is then introduced from connector 70 onto third column80. In one embodiment, third column 80 is within a separate temperaturecontrolling device 120 that allows for a separate temperature controlfor third column 80. At least one analyte is introduced to detector 100from third column 80. Detector 100 may be, but is not limited to a massspectrometer, a thermal conductivity detector, a discharge ionizationdetector, an electron capture detector, a flame photometric detector, aHall electrolytic conductivity detector, a helium ionization detector, anitrogen phosphorus detector, a mass selective detector, aphoto-ionization detector, a pulsed discharge ionization detector, andany other detection device that is now known or hereafter developedsuitable for analyzing and identifying at least one analyte.

In one embodiment, injection device 20 is operably connected to firstcolumn 30 that in turn is operably coupled to heartcut device 40.Heartcut device 40 is operably coupled to second column 60 that in turnis operably coupled to connector 70. Connector 70 is operably coupled tothird column 80 that in turn is operably coupled to detector 100. Theseare in a downstream series with each other.

FIG. 2 illustrates another embodiment of the method of the presentinvention directed to a method for identifying the composition of asample using chromatograph 10 as described in a manner hereinabove thatfurther comprises a fourth column 90. At least one analyte is introducedfrom third column 80 onto fourth column 90. The analyte is thenintroduced from fourth column 90 to detector 100 for analysis andidentification of at least one analyte. In another embodiment, a fifthcolumn 130 is located between fourth column 90 and detector 100.

The method of the present invention may be used to selectively targetspecific analytes in a sample. Heartcut device 40 aids in selectivelytargeting analytes for analysis and identification. Targeted analyteanalysis has a variety of applications such as it may be used in theagricultural industry for determining the composition of pesticides orused to determine the composition of pollutants. Other industryapplications include, but are not limited to, the petroleum industry,the food industry, and the flavoring industry. It will be appreciated byone skilled in the art that the method of the present invention may beused in any situation where current methods of gas chromatography areused.

FIG. 3 illustrates another embodiment of the method of the presentinvention directed to a method for identifying the composition of asample using chromatograph 10 as described in a manner as describedrelating to FIG. 1 that further comprises introducing at least one ofthe heartcut fractions onto first column 30 to further separate thefraction into at least two constituents. At least one of theconstituents is then introduced into heartcut device 40 to furtherseparate the constituent into at least two analytes. FIG. 3 illustratesan alternate embodiment where first column 30, heartcut device 40, andsecond column 60 are all within temperature control device 50. It willbe appreciated by those skilled in the art that there are various wayschromatograph 10 may be configured.

Having described the invention in detail, those skilled in the art willappreciate that modifications of the invention may be made withoutdeparting from the spirit and scope thereof. Therefore, it is notintended that the scope of the invention be limited to the specificembodiments and examples described. Rather, it is intended that theappended claims and their equivalents determine the scope of theinvention.

1. A method for identifying the composition of a sample, comprising thesteps of: introducing said sample onto a first column whereby saidsample is separated into at least two segments; introducing saidsegments into a heartcut device whereby said segments are selectivelyseparated into at least two heartcut fractions; introducing at least oneof said fractions onto a second column whereby said at least onefraction is further separated into at least two analytes; introducing atleast one said analyte from said second column to a gas chromatographyconnector; introducing said analyte from said connector onto a thirdcolumn; introducing said analyte from said third column into a detector;and analyzing said analyte.
 2. The method of claim 1 further comprisingthe step of: introducing said analyte from said third column onto afourth column, wherein said first column is operably coupled to saidheartcut device, said heartcut device is operably coupled to said secondcolumn, said second column is operably connected to said connector, saidconnector is operably connected to said third column, and said thirdcolumn is operably connected to said fourth column.
 3. The method ofclaim 2 further comprising the step of: introducing said analyte fromsaid fourth column onto a fifth column, wherein said fourth column andsaid fifth column are operably connected.
 4. The method of claim 1wherein said sample is introduced onto said first column by an injectingdevice wherein said injecting device is selected from the groupconsisting of a split/splitless injector, an on-column inlet, a thermaldesorption device, a PTV injector, a gas source inlet, a gas switchingvalve, a purge-and-trap system, and a solid phase microextraction. 5.The method of claim 1 wherein said step of introducing said sample ontoa first column and said step of introducing said segments into saidheartcut device occur within a temperature controlling device.
 6. Themethod of claim 5 wherein said temperature controlling device isselected from the group consisting of an oven, and a heating jacket. 7.The method of claim 1 wherein said heartcut device is selected from thegroup consisting of a valve, a SGE heartcut device, a Dean's switch anda Gerstel heartcut device.
 8. The method of claim 1 wherein said columnsare selected from the group consisting of a packed column, a capillarycolumn, a micropacked column, and a microfast column.
 9. The method ofclaim 1 wherein said detector is selected from the group consisting of aflame ionization detector, a mass spectrometer, a thermal conductivitydetector, a discharge ionization detector, an electron capture detector,a flame photometric detector, a Hall electrolytic conductivity detector,a helium ionization detector, a nitrogen phosphorus detector, a massselective detector, a photo-ionization detector, and a pulsed dischargeionization detector.
 10. The method of claim 1 wherein said third columnis contained within a temperature controlling device.
 11. A method foridentifying the composition of a sample, comprising the steps of:introducing said sample onto a first column whereby said sample isseparated into at least two segments; introducing said segments into aheartcut device whereby said segments are selectively separated into atleast two heartcut fractions; introducing at least one of said fractionsonto said first column whereby said heartcut fraction is furtherseparated into at least two constituents; introducing at least one ofsaid constituents into said heartcut device whereby said constituent isfurther separated into at least two analytes; introducing at least oneof said analytes onto a second column; introducing said anaylte fromsaid second column to a gas chromatography connector; introducing saidanalyte from said connector onto a third column; introducing saidanalyte from said third column into a detector; and analyzing saidanalyte.
 12. A method for identifying the composition of a sample usingmultidimensional chromatography, comprising the steps of: introducingsaid sample onto a first column whereby said sample is separated into atleast two segments; introducing said segments into a heartcut devicewhereby said segments are selectively separated into at least twoheartcut fractions and wherein said first column is operably coupled tosaid heartcut device, further wherein said first column and saidheartcut device are in a first temperature controlling device whereinthe temperature of said first temperature controlling device ranges fromabout 40° C. to about 320° C.; introducing at least one of saidfractions onto a second column whereby said at least one fraction isfurther separated into at least two analytes and wherein said heartcutdevice is operably coupled to said second column, further wherein saidsecond column is in said first temperature controlling device;introducing at least one said analyte from said second column to a gaschromatography connector wherein said second column and said connectorare operably coupled; introducing said analyte from said connector ontoa third column wherein said connector and said third column are operablycoupled and wherein said third column is within a second temperaturecontrolling device; introducing said analyte from said third column intoa detector wherein said third column and said detector are operablycoupled; and analyzing said sample.
 13. A multidimensional chromatographcomprising: an introduction device; a first column wherein saidintroduction device introduces a sample onto said first column wherebysaid sample is separated into at least two segments; a heartcut devicewherein said segments are introduced to said heartcut device and wherebysaid segments are selectively separated into at least two heartcutfractions; a second column wherein at least one of said fractions isintroduced and further separated into at least two analytes; a gaschromatography connector wherein at least one of said analytes isintroduced; a third column wherein said analyte is introduced; and adetector wherein said analyte is introduced and identified.
 14. Thechromatograph of claim 14 wherein said columns are selected from thegroup consisting of a packed column, a capillary column, a micropackedcolumn, and a microfast column.
 15. The chromatograph of claim 14wherein said first column is a capillary column with a size of about 30m×0.25 mmID×1 μm df, said second column is a capillary column with asize of about 30 m×0.25 mmID×1 μm df, and said third column is acapillary column with a size of about 1 m×0.10 mmID×0.1 μm df.
 16. Thechromatograph of claim 14 wherein said introduction device is selectedfrom the group consisting of a split/splitless injector, an on-columninlet, a thermal desorption device, a PTV injector, a gas source inlet,a gas switching valve, a purge-and-trap system, and a solid phasemicroextraction.
 17. The chromatograph of claim 14 wherein said firstcolumn and said heartcut device are within a temperature controllingdevice.
 18. The chromatograph of claim 14 wherein said heartcut deviceis selected from the group consisting of a valve, a SGE heartcut device,a Dean's switch and a Gerstel heartcut device.
 19. The chromatograph ofclaim 14 wherein said detector is selected from the group consisting ofa flame ionization detector, a mass spectrometer, a thermal conductivitydetector, a discharge ionization detector, an electron capture detector,a flame photometric detector, a Hall electrolytic conductivity detector,a helium ionization detector, a nitrogen phosphorus detector, a massselective detector, a photo-ionization detector, and a pulsed dischargeionization detector.